Matrix effects on the fast atom bombardment mass spectra of palladium complexes

In an attempt to identify and characterize the intermediates involved in multi‐step palladium catalyzed coupling reactions, under fast atom bombardment (FAB) conditions, the selection of a matrix to enhance ion formation without degrading the palladium complex is critical. In general, it is observed that the analysis of tetrakis(triphenylphosphine)palladiurn(0) using glycerol, m‐nitrobenzyl alcohol or o‐nitrophenyl octyl ether as the FAB matrix compound produces several ions which correspond to complexes of the type PdxLyOz+ (L = PPh3; x = 1‐4; y = 1‐4; z = 0‐2), in addition to clusters containing one or more matrix molecules. FAB mass spectra generated using triethanolamine‐ or tetramethylene sulfone (sulfolane) are observed to contain ions related to the palladium(0) complex with little or no interference from ions related to the oxidation or reduction processes.